U.S. patent number 6,470,970 [Application Number 09/503,276] was granted by the patent office on 2002-10-29 for multiplier digital-hydraulic well control system and method.
This patent grant is currently assigned to Welldynamics Inc.. Invention is credited to Brett Bouldin, Dan Purkis, Richard Rubbo.
United States Patent |
6,470,970 |
Purkis , et al. |
October 29, 2002 |
Multiplier digital-hydraulic well control system and method
Abstract
A system for transmitting hydraulic control signals or hydraulic
power to downhole well tools while significantly reducing the
number of hydraulic lines required. Hydraulic control signals are
furnished at relatively low pressures to actuate a selected well
tool, and the hydraulic pressure is selectively increased over a
threshold level to provide hydraulic power to the well tool. The
hydraulic control actuation signals can be controlled by
selectively pressurizing different hydraulic lines in a selected
sequence and by selectively powering the fluid pressure within a
selected hydraulic line. The combination of selective sequential
actuation and selective fluid pressure provides multiple actuation
combinations for selectively actuating downhole well tools.
Additional combinations can be provided by changing the
pressurization sequence, magnitude, absolute time, duration, and
pressurization profile within a discrete time period.
Inventors: |
Purkis; Dan (Cruden Bay,
GB), Bouldin; Brett (Spring, TX), Rubbo;
Richard (The Woodlands, TX) |
Assignee: |
Welldynamics Inc. (Spring,
TX)
|
Family
ID: |
24001411 |
Appl.
No.: |
09/503,276 |
Filed: |
February 14, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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133747 |
Aug 13, 1998 |
6179052 |
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Current U.S.
Class: |
166/374; 166/319;
166/53; 166/72 |
Current CPC
Class: |
E21B
23/04 (20130101); E21B 33/0355 (20130101); E21B
34/16 (20130101); E21B 47/12 (20130101); F15B
13/06 (20130101); E21B 34/10 (20130101) |
Current International
Class: |
E21B
47/12 (20060101); E21B 34/16 (20060101); E21B
34/00 (20060101); E21B 034/10 () |
Field of
Search: |
;166/72,53,50,319,363,364,375,374 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0344060 |
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Nov 1989 |
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EP |
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2052052 |
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Sep 1971 |
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FR |
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2335216 |
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Sep 1999 |
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GB |
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WO97/47852 |
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Dec 1997 |
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WO |
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WO99/47788 |
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Sep 1999 |
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WO |
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WO00/09855 |
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Feb 2000 |
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WO |
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Other References
International Search Report Application No. PCT/US01/02306. .
International Search Report Application No.
PCT/US00/12329..
|
Primary Examiner: Bagnell; David
Assistant Examiner: Stephenson; Daniel
Attorney, Agent or Firm: Herman; Paul I. Imwalle; William M.
Smith; Marlin R.
Parent Case Text
This patent application is a continuation-in-part patent
application of U.S. Ser. No. 09/133,747 filed Aug. 13, 1998 now
U.S. Pat. No. 6,179,052, entitled "Digital-Hydraulic Well Control
System".
Claims
What is claimed is:
1. An apparatus for transmitting pressurized fluid between a
wellbore surface and a well tool located downhole in the wellbore,
comprising: at least two hydraulic lines engaged with the well tool
for conveying the fluid to the well tool, each hydraulic line
providing communication control signals to actuate the well tool
and providing fluid pressure to operate the well tool; an actuator
engaged with each hydraulic line and with the well tool for
selectively operating the well tool; and a controller selectively
pressurizing the fluid within each hydraulic line in a
predetermined fluid pressure sequence to select the well tool for
actuation and thereby initiate operation of the actuator, and the
controller further increasing the pressure within a selected at
least one of the hydraulic lines, thereby causing the actuator to
operate the well tool.
2. An apparatus as recited in claim 1, wherein said actuator is
capable of identifying a selected fluid pressure sequence and for
actuating the well tool in response to said fluid pressure
sequence.
3. An apparatus as recited in claim 1, wherein said controller
includes a clock for selectively pressurizing the fluid at selected
time intervals.
4. An apparatus as recited in claim 1, wherein said controller is
capable of selectively pressurizing fluid in each hydraulic line in
a selected sequence.
5. An apparatus as recited in claim 1, wherein said controller is
capable of selectively pressurizing fluid in each hydraulic line
for a selected time period.
6. An apparatus as recited in claim 1, further comprising a third
hydraulic line engaged with the well tool for returning the fluid
to the wellbore surface.
7. An apparatus as recited in claim 6, wherein said controller
includes a fluid sensor for detecting the return of fluid through
said third hydraulic line when another hydraulic line is
pressurized.
8. An apparatus as recited in claim 1, wherein at least three
hydraulic lines form a closed loop for circulating fluid downhole
and for returning the fluid to the wellbore surface through at
least one of said three hydraulic lines, further comprising means
for detecting the return of fluid through a hydraulic line to the
wellbore surface when another hydraulic line is pressurized.
9. An apparatus as recited in claim 1, wherein at least three well
tools are each engaged with two or more hydraulic lines, further
comprising a separate actuator engaged with each of said hydraulic
lines and said well tools for actuating one of the well tools by
the selective pressurization of one hydraulic line.
10. An apparatus as recited in claim 1, wherein at least three well
tools are each engaged with two or more hydraulic lines, further
comprising an actuator engaged with said hydraulic lines and said
well tools for actuating one of the well tools by the selective
pressurization of two hydraulic lines.
11. An apparatus as recited in claim 1, wherein said actuator is
capable of incrementally operating in response to a selected
quantity of fluid.
12. An apparatus as recited in claim 1, wherein said actuator is
capable of operating following a selected time interval.
13. An apparatus as recited in claim 1, wherein said actuator is
capable of operating in response to a selected fluid pressure
sequence.
14. An apparatus for transmitting pressurized fluid between a
wellbore surface and a well tool located downhole in the wellbore,
comprising: at least two hydraulic lines engaged with the well tool
for conveying the fluid to the well tool, each hydraulic line
providing communication control signals to actuate the well tool
and providing fluid pressure to operate the well tool; and a
controller selectively pressurizing the fluid within each hydraulic
line and thereby providing the communication control signals in a
predetermined fluid pressure sequence to select the well tool for
actuation, and the controller applying a predetermined pressure to
actuate the well tool.
15. An apparatus as recited in claim 14, further comprising an
actuator engaged with said hydraulic lines and with the well tool
for identifying a selected fluid pressure sequence, for identifying
said selected fluid pressure, and for actuating the well tool in
response to said fluid pressure sequence and selected fluid
pressure.
16. An apparatus as recited in claim 14, wherein said controller
selectively pressurizes fluid within a selected hydraulic line at a
selected magnitude in combination with a selected fluid pressure
sequence to actuate a selected well tool.
17. An apparatus as recited in claim 14, wherein said controller
selectively pressurizes fluid within a selected hydraulic line at a
selected pressure distribution, in combination with a selected
fluid pressure sequence, to actuate a selected well tool.
18. An apparatus as recited in claim 14, wherein said controller
selectively pressurizes fluid within a selected hydraulic line at a
selected time interval, in combination with a selected fluid
pressure sequence, to actuate a selected well tool.
19. An apparatus as recited in claim 18, wherein said controller
selectively pressurizes fluid within a selected hydraulic line at a
selected distribution within said selected time interval.
20. An apparatus as recited in claim 14, wherein said controller
includes a fluid sensor for detecting the return of fluid through
said third hydraulic line when another hydraulic line is
pressurized.
21. A method of hydraulically controlling multiple well tools in a
well, the method comprising the steps of: interconnecting a
plurality of hydraulic lines to each of the tools; and selecting a
first one of the tools for actuation thereof by generating a first
predetermined pressure on a first combination of the hydraulic
lines, the first pressure being generated on the first combination
of the hydraulic lines in a first predetermined sequence in which
the first pressure is applied successively to selected ones of the
first combination of the hydraulic lines.
22. The method according to claim 21, further comprising the step
of selecting a second one of the tools for actuation thereof by
generating the first predetermined pressure on the first
combination of the hydraulic lines, the first pressure being
generated on the first combination of the hydraulic lines in a
second predetermined sequence.
23. The method according to claim 21, further comprising the step
of selecting a second one of the tools for actuation thereof by
generating the first predetermined pressure on a second combination
of the hydraulic lines, the first pressure being generated on the
second combination of the hydraulic lines in a second predetermined
sequence.
24. The method according to claim 21, further comprising the step
of permitting fluid communication between at least one of the first
combination of the hydraulic lines and an actuator of the first
well tool in response to the selecting step.
25. The method according to claim 24, wherein the actuator is
pressure balanced prior to the selecting step.
26. The method according to claim 24, wherein the actuator is
operative in response to pressure applied to first and second ports
thereof, wherein the first and second ports are in fluid
communication with each other prior to the selecting step, and
wherein the selecting step further comprises preventing fluid
communication between the first and second ports.
27. The method according to claim 26, wherein the selecting step
further comprises permitting fluid communication between a first
hydraulic line of the first combination of hydraulic lines and the
first port, and permitting fluid communication between a second
hydraulic line of the first combination of hydraulic lines and the
second port.
28. The method according to claim 24, wherein the fluid
communication permitting step further comprises permitting fluid
communication between the actuator and each of first and second
hydraulic lines of the first combination of the hydraulic lines,
and wherein the method further comprises the step of generating a
second pressure on the first hydraulic line after the fluid
communication permitting step, thereby transmitting fluid from the
first hydraulic line to the actuator.
29. The method according to claim 28, wherein the second pressure
generating step further comprises receiving fluid from the actuator
into the second hydraulic line in response to transmitting fluid
from the first hydraulic line to the actuator.
30. The method according to claim 28, wherein in the second
pressure generating step, the second pressure is greater than the
first predetermined pressure.
31. The method according to claim 21, further comprising the step
of preventing selection of the first tool for actuation thereof by
generating the first pressure on a first hydraulic line of the
first combination of the hydraulic lines, the first hydraulic line
not being included in the selected ones of the first combination of
the hydraulic lines.
32. The method according to claim 21, further comprising the step
of preventing selection of the first tool for actuation thereof by
generating fluid pressure on the first combination of the hydraulic
lines in a second sequence.
33. A well control system, comprising: a first valve assembly
including a first actuation control device, a first actuator and a
first valve; and first and second hydraulic lines interconnected to
the first actuation control device, the first actuation control
device responding to a first sequence of a first predetermined
fluid pressure generated on the first hydraulic line and then a
second predetermined fluid pressure generated on the second
hydraulic line to permit fluid communication between the first
actuator and at least one of the first and second hydraulic lines
for operation of the first valve.
34. The well control system according to claim 33, wherein the
first predetermined fluid pressure is substantially equal to the
second predetermined fluid pressure.
35. The well control system according to claim 33, wherein the
first actuator is pressure balanced by the first actuation control
device while the first actuation control device prevents fluid
communication between the first actuator and at least one of the
first and second hydraulic lines.
36. The well control system according to claim 33, further
comprising a second valve assembly including a second actuation
control device, a second actuator and a second valve, the first and
second hydraulic lines being interconnected to the second actuation
control device, and the second actuation control device responding
to a second sequence of the first predetermined fluid pressure
generated on the second hydraulic line and then the second
predetermined fluid pressure generated on the first hydraulic line
to permit fluid communication between the second actuator and at
least one of the first and second hydraulic lines for operation of
the second valve.
37. The well control system according to claim 33, further
comprising a third hydraulic line interconnected to the first
actuation control device, the first actuation control device
preventing fluid communication between the first actuator and at
least one of the first and second hydraulic lines when fluid
pressure is generated on the third hydraulic line.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a system for controlling the
production of hydrocarbons and other fluids from downhole wells.
More particularly, the invention relates to a system for providing
hydraulic control signals and power through multiple hydraulic
lines by controlling power distribution to selective hydraulic
lines.
Various tools and tool systems have been developed to control,
select or regulate the production of hydrocarbon fluids and other
fluids produced downhole from subterranean wells. Downhole well
tools such as sliding sleeves, sliding windows, interval control
lines, safety valves, lubricator valves, and gas lift valves are
representative examples of control tools positioned downhole in
wells.
Sliding sleeves and similar devices can be placed in isolated
sections of the wellbore to control fluid flow from such wellbore
section. Multiple sliding sleeves and interval control valves
(ICVs) can be placed in different isolated sections within
production tubing to jointly control fluid flow within the
particular production tubing section, and to commingle the various
fluids within the common production tubing interior. This
production method is known as "comingling" or "coproduction".
Reverse circulation of fluids through the production of tubing,
known as "injection splitting", is performed by pumping a
production chemical or other fluid downwardly into the production
tubing and through different production tubing sections.
Wellbore tool actuators generally comprise short term or long term
devices. Short term devices include one shot tools and tool having
limited operating cycles. Long term devices can use hydraulically
operated mechanical mechanisms performing over multiple cycles.
Actuation signals are provided through mechanical, direct pressure,
pressure pulsing, electrical, electromagnetic, acoustic, and other
mechanisms. The control mechanism may involve simple mechanics,
fluid logic controls, timers, or electronics. Motive power to
actuated the tools can be provided through springs, differential
pressure, hydrostatic pressure, or locally generated power.
Long term devices provide virtually unlimited operating cycles and
are designed for operation through the well producing life. These
devices are particularly useful in subsea wells and deep horizontal
wells. One type of long term safety valve device closes the tubing
interior with spring powered force when the hydraulic line pressure
is lost. Other electrical and hydraulic combination powered systems
have been developed for downhole use, and sensors can verify proper
operation of tool components.
Interval control valve (ICV) activation is typically accomplished
with mechanical techniques such as a shifting tool deployed from
the well surface on a workstring or coiled tubing. This technique
is expensive and inefficient because the surface controlled rigs
may be unavailable, advance logistical planning is required, and
hydrocarbon production is lost during operation of the shifting
tool. Alternatively, electrical and hydraulic umbilical lines have
been used to remotely control one or more ICVs without reentry into
the wellbore.
Control for one downhole tool can be hydraulically accomplished by
connecting a single hydraulic line to a tool such as an ICV or a
lubricator valve, and by discharging hydraulic fluid from the line
end into the wellbore. This technique has several limitations as
the hydraulic fluid exits the wellbore because of differential
pressures between the hydraulic line and the wellbore. Time delays
in the propagation of pressure through several kilometers of thin
hydraulic line, compressibility of the hydraulic fluid, and line
friction impedes efficient hydraulic fluid operation. Additionally,
the setting depths are limited by the maximum pressure that a
pressure relief valve can hold between the differential pressure
between the control line pressure and the production tubing when
the system is at rest. These limitations restrict single line
hydraulics to relatively low differential pressure applications
such as lubricator valves and ESP sliding sleeves. Further,
discharge of hydraulic fluid into the wellbore comprises an
environmental discharge and risks backflow and particulate
contamination into the hydraulic system. To avoid such
contamination and corrosion problems, a closed loop hydraulic
system would be preferred over hydraulic fluid discharge valves,
however closed loop systems require at least one additional
hydraulic line in the narrow wellbore confines.
Various proposals have been made for multiple tool operation
through a single hydraulic line. U.S. Pat. No. 4,660,647 to Richart
(1987) disclosed a system for changing downhole flow paths by
providing different plug assemblies suitable for insertion within a
side pocket mandrel downhole in the wellbore. In U.S. Pat. No.
4,796,699 to Upchurch (1989), an electronic downhole controller
received pulsed signals for operating multiple well tools. In U.S.
Pat. No. 4,942,926 to Lessi (1990), solenoid valves directed
hydraulic fluid pressure from a single line to control different
operations, and a spring return device facilitated return of the
components to the original position. A second hydraulic line
provided dual operation of the same tool function by controlling
hydraulic fluid flow in different directions. Similarly, U.S. Pat.
No. 4,945,995 to Thulance et al. (1990) disclosed an electrically
operated solenoid valve for selectively controlling operation of a
hydraulic line for opening downhole wellbore valves.
Other downhole well tools use two hydraulic lines to control a
single tool. In U.S. Pat. No. 3,906,726 to Jameson (1975), a manual
control disable valve and a manual choke control valve controlled
the flow of hydraulic fluid on either side of a piston head. In
U.S. Pat. No. 4,197,879 to Young (1980), and in U.S. Pat. No.
4,368,871 to Young (1983), two hydraulic hoses controlled from a
vessel were selectively pressurized to open and close a lubricator
valve during well test operations. A separate control fluid was
directed by each hydraulic hose so that one fluid pressure opened
the valve and a different fluid pressure closed the valve. In U.S.
Pat. No. 4,476,933 to Brooks (1984), a piston shoulder functioned
as a double acting piston in a lubricator valve, and two separate
control lines were connected to conduits and to conventional
fittings to provide high or low pressures in chambers on opposite
sides of the piston shoulder. In U.S. Pat. No. 4,522,370 to Noack
et al. (1985), a combined lubricator and retainer valve was
operable with first and second pressure fluids and pressure
responsive members, and two control lines provided two hydraulic
fluid pressures to the control valve. Multiple hydraulic line
techniques are typically inefficient because the volume of
hydraulic lines required for multiple downhole tools cannot fit
through packers and wellheads.
To avoid multiple hydraulic lines, other techniques have attempted
to establish an operating sequence for well tools. In U.S. Pat. No.
5,065,825 to Bardin et al. (1991), a solenoid valve was operated in
response to a predetermined sequence to move fluid from one
position to another. A check valve permitted discharge of oil into
a reservoir to replenish the reservoir oil pressure. Other systems
use electronic controllers downhole in the wellbore, however
electronics are susceptible to temperature induced deterioration
and other reliability problems.
Mechanical shifting devices have limitations in deep and horizontal
wellbores. Frictional loads on the tool can encumber tool
operation. The tool string weight in horizontal wells decentralizes
the tool and reduces the ability of the tool to maintain an optimal
position within the wellbore. A lack of surface feedback prevents
confirmation of tool operation such as sleeve movement and
latching. High friction loads can indicate tensile or compressive
load indicators, leading to inaccurate assumptions regarding proper
tool deployment.
Downhole hydraulic lines in a wellbore can extend for thousands of
feet into the wellbore. In large wellbores having different
production zones and multiple tool requirements, large numbers of
hydraulic lines are required. Each line significantly increases
installation costs and the number of components potentially subject
to failure. The propagation time necessary to transfer hydraulic
fluid pressure, and pressure gradients within each hydraulic fluid
line, can limit effective well control responses. The effectiveness
of hydraulic fluid lines is further limited by hydraulic lines that
become pinched or otherwise damaged.
Accordingly, a need exists for an improved well control system
capable of avoiding the limitations of prior art devices. The
system should be reliable, should be adaptable to different tool
configurations and combinations, and should be inexpensive to
deploy.
SUMMARY OF THE INVENTION
The present invention provides a system for transmitting
pressurized fluid between a wellbore surface and a well tool
located downhole in the wellbore. The comprises at least two
hydraulic lines engaged with the well tool for conveying the fluid
to the well tool. Each hydraulic line is capable of providing
communication control signals to actuate the well tool and of
providing fluid pressure to operate the well tool, and a controller
for selectively pressurizing the fluid within each hydraulic line
to provide said communication signals to the well tool in a
selected fluid pressure sequence or a selected fluid pressure or
combination to actuate the well tool. The controller is further
capable of increasing the pressure within one of said hydraulic
lines to operate the well tool.
A return line can convey hydraulic fluid from the well tools to the
wellbore surface, and an actuator can be engaged between each
hydraulic line and each well tool to be actuatable in response to
different variables to initiate well tool operation. Useful
variables include sequential operation of control lines, selective
application of power to control lines, through time operated
sequences of pulses or pressure application, through combinations
of coded sequences, through metering of an absolute amount of fluid
flow to initiate tool activation, and others.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a two hydraulic line system for providing
hydraulic pressure control and power to well tools.
FIG. 2 illustrates a graph showing a hydraulic line pressure code
for providing hydraulic control and power capabilities through the
same hydraulic line.
FIG. 3 illustrates a three well tool and three hydraulic line
apparatus.
FIG. 4 illustrates a four line system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention provides unique operation for downhole well tools by
providing multiple power and sequential logic circuit control
combinations with minimal hydraulic lines. Such logic circuitry is
analogous to electrical and electronics systems and incorporates
Boolean Logic using "AND" and "OR" gates in the form of hydraulic
switches. Using this unique concept, digital control capability, or
"digital-hydraulics" can be adapted to the control of downhole well
tools such as ICVs and other downhole tools.
FIG. 1 illustrates two hydraulic lines 10 and 12 engaged with pump
such as controller 14 for providing hydraulic pressure to fluid
(not shown) in lines 10 and 12. Lines 10 and 12 are further engaged
with downhole well tools 16 and 18 for providing hydraulic fluid
pressure to tools 16 and 18. Controller 14 can selectively control
the fluid pressure within lines 10 and 12 and can cooperate with
one or more hydraulic control means or hydraulic manifolds such as
actuator 20 located downhole in the wellbore in engagement with
lines 10 and 12 and with tools 16 and 18. Selective control over
the distribution of hydraulic fluid pressure can be furnished and
controlled with pump 14 at the wellbore surface, or with actuator
20 downhole in the wellbore. Control signals to tools 16 and 18 and
actuator 20 can be provided within a different pressure range as
that required for actuation of tools 16 and 18, and such pressure
range or ranges can be higher, lower, or overlapping. Controller 14
can incorporate a fluid sensor to detect fluid returned through
return line to the well surface, or a different fluid sensor can be
incorporated.
FIG. 2 illustrates one combination of communication and power
functions through the same hydraulic tubing, conduit, passage or
line such as line 10 wherein the control signals are provided at
lower pressures than the power actuation pressures. Pressure is
plotted against time, and the hydraulic pressure is initially
raised above the communication threshold but below the power
threshold. Within this pressure range, communication signals and
controls can be performed through the hydraulic line. The line
pressure is raised to a selected level so that subsequent powering
up of the hydraulic line pressure raises the line pressure to a
certain level. Subsequent actuation of the well control devices,
normally delayed as the pressure builds up within the long
hydraulic tubing, occurs at a faster rate because the line is
already pressurized to a certain level. The ready state pressure
can be maintained slightly below the operation pressure so that a
relatively small increase in fluid pressure activates the well
tool.
The invention further permits the use of additional hydraulic lines
and combinations of hydraulic lines and controllers to provide a
hydraulically actuated well control and power system. One
embodiment of the invention is based on the principle that a
selected number of hydraulic control lines can be engaged with a
tool and that control line combinations can be used for multiple
purposes. For example, a three control line system could use a
first line for hydraulic power such as moving a hydraulic cylinder,
a second line to provide a return path for returning fluid to the
initial location, and all three lines for providing
digital-hydraulic code capabilities. Such code can be represented
by the following Table:
Hydraulic Lines #1 #2 #3 Digital Equation Numeric Value Lines 0 0 0
0 .times. 2.sup.2 + 0 .times. 2.sup.1 + 0 .times. 2.sup.0 = 0 0 0 1
0 .times. 2.sup.2 + 0 .times. 2.sup.1 + 1 .times. 2.sup.0 = 1 0 1 0
0 .times. 2.sup.2 + 1 .times. 2.sup.1 + 0 .times. 2.sup.0 = 2 0 1 1
0 .times. 2.sup.2 + 1 .times. 2.sup.1 + 1 .times. 2.sup.0 = 3 1 0 0
1 .times. 2.sup.2 + 0 .times. 2.sup.1 + 0 .times. 2.sup.0 = 4 1 0 1
1 .times. 2.sup.2 + 0 .times. 2.sup.1 + 1 .times. 2.sup.0 = 5 1 1 0
1 .times. 2.sup.2 + 1 .times. 2.sup.1 + 0 .times. 2.sup.0 = 6 1 1 1
1 .times. 2.sup.2 + 1 .times. 2.sup.1 + 1 .times. 2.sup.0 = 7
If "1" represents a pressurized line and if "0" represents an
unpressurized line, then the combination of hydraulic lines
provides the described code format for a binary communication code.
Because the hydraulic line operation can use both a pressurized and
an unpressurized line in a preferred embodiment of the invention,
codes 000 and 111 would not be used in this embodiment. However, if
one or more lines discharged fluid to the outside of the line to
the tubing exterior, another tool, or other location, codes 000 and
111 would be useful for transmitting power or signals. If codes 000
and 111 are excluded from use in the inventive embodiment
described, the following six codes are available for tool
control:
#1 #2 #3 0 0 1 - 1 0 1 0 - 2 0 1 1 - 3 1 0 0 - 4 1 0 1 - 5 1 1 0 -
6
These codes are unique and can be grouped to provide six
independent degrees of freedom to a hydraulic network. Different
combinations are possible, and one combination permits the
operation of three well tools such as ICVs 22, 24, and 26 having
double actuated floating pistons as illustrated in FIG. 3. Lines
28, 30 and 32 are engaged between pump 14 and ICVs 22, 24, and 26.
Lines 28, 30, and 32 could provide an opening code 001 for ICV 22.
After a sufficient time lapse for all well tools such as the ICVs
has occurred to detect and register the 001 code, the line pressure
can be raised above the power threshold until a selected pressure
level is achieved. The pressure can be held constant at such level,
or varied to accomplish other functions. The selected well tool
such as ICV 22 is actuated, and return fluid is directed back
through one or more of the lines designated as a "0" ,
unpressurized line. Next, control line 32 is bled to zero and the
entire system is at rest, leaving ICV 22 fully open until further
operation. To open ICV 24, control lines 28, 30, and 32 can be
coded and operated as illustrated. After sufficient time has
passed, the system pressure can be increased to operate ICV 24. The
degrees of control freedom and operating controls can be
represented by the following instructions:
Hydraulic Line Number
28 30 32 0 0 1 Open ICV 22 0 1 0 Close ICV 22 0 1 1 Open ICV 24 1 0
0 Close ICV 24 1 0 1 Open ICV 26 1 1 0 Close ICV 26 ##EQU1## where
X equals the number of independently controlled ICVs, and N equals
the number of control lines. where X equals the number of
independently controlled ICVs, and N equals the number of control
lines.
The unique combination of valves and other components within each
control module provides for unique, selected operating functions
and characteristics. Operation of each line can be required in a
particular sequence to match with the operability of a downhole
tool. Depending on the proper sequence and configuration,
pressurization of a hydraulic line can actuate one of the tools
without actuating other tools in the system. Alternatively, various
combinations of well tools could be actuated with the same
hydraulic line if desired.
Another embodiment of the invention is described below, wherein the
number of combinations per fixed number of hydraulic lines can be
significantly increased by reordering the pressure sequence.
"Sequence" as used herein relates to an order of succession or
arrangement in a related or continuous series. For a two line
system, line #1 can be pressurized first and line #2 can be
pressurized second, or vice versa as illustrated below.
Hydraulic Lines #1 #2 Digital Sequence 1 1 1(i) 1(ii) 1 1 1(ii)
1(i)
By sequentially reordering the distribution of pressure to
hydraulic lines #1 and #2, a new variable of "relative order"
permits additional pressure combinations to be incorporated into a
well tool actuation system. Power can be added to the system from
controller 20 to operate the selected well tool, and can be
accomplished by providing additional hydraulic pressure to one or
both hydraulic lines. A third "return line" can be added to convey
hydraulic fluid to the well surface in a closed loop system, and
the return line can be engaged with well tools operable by both the
#1 and #2 control lines. Because both lines #1 and #2 end at the
actuation pressure, the system is ultimately "blind" to the
sequence order and can be reinitiated without depending upon prior
sequences. This system is particularly useful for multiple
hydraulic lines wherein the sequence combinations increase
exponentially.
For three hydraulic lines:
Hydraulic Lines Digital Sequence #1 #2 #3 #1 #2 #3 1 0 0 1(i) 0 1 0
1(i) 0 0 1 1(i) 1 1 0 1(i) 1(ii) 1 1 0 1(ii) 1(i) 1 0 1 1(i) 1(ii)
1 0 1 1(ii) 1(i) 0 1 1 1(i) 1(ii) 0 1 1 1(ii) 1(i) 1 1 1 1(i) 1(ii)
1(iii) 1 1 1 1(i) 1(iii) 1(ii) 1 1 1 1(ii) 1(i) 1(iii) 1 1 1 1(ii)
1(iii) 1(i) 1 1 1 1(iii) 1(i) 1(ii) 1 1 1 1(iii) 1(ii) 1(i)
From this example, multiple signal combinations can be created from
a relatively small number of hydraulic lines. After the
communication control signals have been transmitted by controller
14 through the hydraulic lines to actuate the selected well tools,
power-up of the system can be accomplished by increasing the fluid
pressure within selected hydraulic lines to operate the actuated
well tool or tools. Following such event, continued system
operation and additional sequences can be accomplished regardless
of prior hydraulic line pressurization. This can be accomplished in
different ways and occurs automatically for the last six sequences
listed above because each of the three lines is ultimately
pressurized. For the other sequences listed above, the well tools
or actuators engaged with such well tools can be configured to
reset to a particular state following completion of a time period
or operation sequence.
In addition to alternatively to the sequential system described
above, the invention permits the variable of selective power to
increase the number of code sequence combinations available through
a limited number of hydraulic lines. For a three line system having
a return line the combination of sequential control would provide
the following code combinations:
Hydraulic Lines Digital Sequence #1 #2 #3 #1 #2 #3 0 1 1 0 1(i)
1(ii) 0 1 1 0 1(ii) 1(i)
For a three line system wherein an increased actuation pressure is
applied by controller 14 through selected hydraulic lines and one
line is dedicated as a return line for closed loop operations, the
number of code combinations can be increased as follows where "p"
represents the selective application of pressure at a higher or
lower activation pressure:
Hydraulic Lines Digital Sequence #1 #2 #3 #1 #2 #3 0 1 1 0 1(i)p
1(ii) 0 1 1 0 1(i) 1(ii)p 0 1 1 0 1(ii)p 1(i) 0 1 1 0 1(ii)
1(i)p
The invention can be applied to a four line system as illustrated
in FIG. 4, wherein control lines 40, 42, 44, and 46 are actuated or
monitored by controller 48. Actuator 50 is engaged with tool 52,
actuator 54 is engaged with tool 56, actuator 58 is engaged with
tool 60, actuator 62 is engaged with tool 64, actuator 66 is
engaged with tool 68, actuator 70 is engaged with tool 72, and
actuator 74 is engaged with tool 76.
All four lines can be used to generate different system
combinations similar to the three line system described above. For
a four line system wherein one line is dedicated as a return line
for closed loop operations, the number of code combinations can be
illustrated as follows:
Hydraulic Lines Digital Sequence #1 #2 #3 #4 #1 #2 #3 #4 0 1 1 1 0
1(i) 1(ii) 1(iii)p 0 1 1 1 0 1(i) 1(ii)p 1(iii) 0 1 1 1 0 1(i)p
1(ii) 1(iii) 0 1 1 1 0 1(i) 1(iii) 1(ii)p 0 1 1 1 0 1(i) 1(iii)p
1(ii) 0 1 1 1 0 1(i)p 1(iii) 1(ii) 0 1 1 1 0 1(ii) 1(i) 1(iii)p 0 1
1 1 0 1(ii) 1(i)p 1(iii) 0 1 1 1 0 1(ii)p 1(i) 1(iii) 0 1 1 1 0
1(ii) 1(iii) 1(i)p 0 1 1 1 0 1(ii) 1(iii)p 1(i) 0 1 1 1 0 1(ii)p
1(iii) 1(i) 0 1 1 1 0 1(iii) 1(i) 1(ii)p 0 1 1 1 0 1(iii) 1(i)p
1(ii) 0 1 1 1 0 1(iii)p 1(i) 1(ii) 0 1 1 1 0 1(iii) 1(ii) 1(i)p 0 1
1 1 0 1(iii) 1(ii)p 1(i) 0 1 1 1 0 1(iii)p 1(ii) 1(i)
As illustrated by these examples of sequential application and
selective power, significant code sequences can be transmitted
through relatively few hydraulic lines. The invention can be
extended into additional code combinations by overlaying sequential
methods over the selective pressure techniques described herein. A
four line system application could generate over 130 separate codes
as controller 14 applies power to selected pressure lines. One such
sequence of code combinations having hydraulic lines first actuated
in the order (i), (ii), and (iii) is partially illustrated as
follows:
Digital Sequence #1 #2 #3 #4 0 1(i) 1(ii)p(i) 1(iii)p(ii) 0 1(i)
1(ii)p(ii) 1(iii)p(i) 0 1(i)p(i) 1(ii)p(ii) 1(iii) 0 1(i)p(ii)
1(ii)p(i) 1(iii) 0 1(i)p(i) 1(ii) 1(iii)p(ii) 0 1(i)P(ii) 1(ii)
1(iii)p(i)
In addition to the sequences described above, additional code
sequences can be achieved if the relative pressure p is varied
according to magnitude. Using this power level variable in
combination with the selective power combinations or the sequential
operation options described above, virtually unlimited code
sequence combinations can be achieved. For example, pressure
combinations can be accomplished at 2000 psi, 3000 psi, 3200 psi,
or at other selected pressures. By adding the pressure variable to
the other system variables identified above, multiple well
combinations can be created with relatively few hydraulic
lines.
In addition to the pressure magnitude variable described above,
pressure distribution changes can be used to introduce another
variable into the digital sequence. Pressure distribution changes
can be formulated as a series of threshold levels, as a curve
having discrete attributes or located within a selected time
interval, or combination of these factors. The signal can be formed
to efficiently correlate with the response of the hydraulic lines,
actuator traits, and other factors.
As shown in FIG. 3, actuators 80 and 82 are engaged with tool 22.
Actuator 80 includes spring loaded check 83, check valve 84, pilot
operated valve 86, and pilot operated valve 88. Actuator 82
includes check 90, spring loaded check valve 92, pilot operated
valve 94, and pilot operated valve 96. Other combinations of
actuators can be substituted for the embodiment shown. For example,
actuator 80 can be configured as a metering device which
incrementally permits a limited movement following flow of a
selected amount of fluid. Tool operation can be performed when a
selected amount of fluid flow has been accomplished, thereby
providing a reliable technique for avoiding premature or late
operation of the selected tool. Such embodiment of the invention
eliminates or substantially reduces the impact of constricted flow
lines or debris or leaks which could cause premature or late
operation of a pressure activated well tool.
By providing multiple combinations of communication and power
capabilities through relatively few hydraulic lines, the invention
significantly eliminates problems associated with limited available
space and with pressure transients. In deep wellbores, the
hydraulic lines are very long and slender, and this combination
significantly limits the hydraulic line ability to quickly transmit
pressure pulses or changes from the wellbore surface to a downhole
tool location. In deep wellbores, five to ten minutes could be
required before the hydraulic lines are accurately coded for the
communication of sequenced controls. If some of the ICVs were
located at relatively shallow depths in the wellbore, such ICVs
would receive the code long before other ICVs located deep in the
wellbore, thereby creating confusion on the digital-hydraulics
control circuit.
This problem can be resolved by dedicating certain lines for
communication signals and other lines for power. Communication
signal lines could operate at relatively low pressures while the
power lines could operate within higher pressure ranges.
Alternatively, a preferred embodiment of the invention can utilize
such time delay characteristics as a design variable by applying
the communication coding early at relatively low pressures where
the ICVs receive the codes but are not activated, and then
increasing the pressure above a selected activation threshold to
move the ICVs. This permits communication and power to be
transmitted through the same hydraulic lines, and further uses the
communication pressures to initially raise the line pressures to a
selected level and thereby shorten the required power-up time.
The invention uniquely permits selective control of downhole tools
while providing for recirculation of fluid within the hydraulic
lines such as lines 10 and 12. Code combinations can be made so
that fresh hydraulic fluid can be added to lines at the surface,
and existing hydraulic fluid can be withdrawn from the system at
the wellbore surface as the fresh hydraulic fluid is added. For
example, a well tool such as an ICV can be pumped open with an open
code "1010" (wherein the first and third lines are pressurized and
the second and fourth lines are unpressurized) and pumped closed
with a code "0110" (wherein the second and third codes are
pressurized and the first and fourth codes are unpressurized). If
fluid for an open tool condition was received from the first line
and returned through the second line, then closing the tool would
take fluid from the third line and return such fluid to the
wellbore surface through the fourth line. Under such configuration,
the fluid in each line would always travel in the same direction
and could be circulated throughout the entire system without being
reciprocated within the same line. This feature of the invention
permits replacement of all hydraulic fluid during routine
maintenance operations without withdrawing system components from
the wellbore. This ability to change the hydraulic fluid from the
wellbore surface significantly reduces lost production time and the
resulting cost associated with such operations.
The ability to circulate fresh hydraulic fluid into the lines
significantly prolongs the life of system components. Contaminant
build-up and wear caused by fluid particles and seal debris is
reduced, thereby prolonging the useful system life. In another
embodiment of the invention, a fluid recirculation unit can be
located downhole in the wellbore to permit hydraulic fluid to be
recirculated and flushed within a downhole circulation loop. By
eliminating the need to pump fresh fluid to each downhole tool
through the line length positioned between the surface and the
downhole tools, this feature of the invention would reduce the
quantity of hydraulic fluid necessarily flushed through the system.
In other embodiments of the invention, a selected line known to
have heavy use could serve as the circulation line, thereby
providing the convenient conduit for circulating fresh hydraulic
fluid.
By controlling all hydraulic fluid flow from the wellbore surface,
and by providing recirculation to the wellbore surface, unique
monitoring capabilites are provided. The amount of fluid entering a
line or leaving a return line can be monitored to determine and to
verify the position and operation of downhole well tools.
Similarly, the presence of fluid movement into a line without equal
return fluid would provide information such as the presence of
leaks within the system. In systems having four or more lines, test
operation of the multiple lines could identify the leak source in
the downhole tool or in the defective hydraulic line.
Real-time monitoring of the hydraulic fluid intake and outflow also
provides a significant function in preventing over pressurization
of a downhole tool such as a valve. By providing a closed volume
and by monitoring the hydraulic fluid flow, overpressurization of
the fluid intake line is prevented, thereby eliminating operator
induced overpressurization and failure of the downhole tool.
Flowmeters can operate by position sensing, by force deflection, or
by other mechanisms.
The ability to control all hydraulic fluid movement from the
wellbore surface also provides the unique function of reliable,
infinitely variable control over downhole well tools. Downhole
valves can be partially opened and closed to a selected degree, and
such movement can be controlled partially and incrementally without
requiring complete opening or closure of the tool during any given
cycle. Infinitely variable tool control provides control not only
over tool movement, displacement or position, but also over the
power or force exerted by a downhole tool. Orifices can be
selectively opened or closed, pistons can be moved in different
directions, valves can be moved, the orientation of tool elements
can be changed, perforating guns can be activated, and other
mechanical operations can be accomplished downhole in the wellbore
with minimal surface intervention. This capability provides
significant design flexibility in the creation of downhole well
tools and the functions performed by each tool.
The invention is applicable to many different tools including
downhole devices having more than one operating mode or position
from a single dedicated hydraulic line. Such tools include tubing
mounted ball valves, sliding sleeves, lubricator valves, and other
devices. The invention is particularly suitable for devices having
a two-way piston, open/close actuator for providing force in either
direction in response to differential pressure across the piston.
For a three line system providing fifteen codes, various code
combinations can be created for different systems. For example, the
fifteen codes could handle fifteen single acting pistons such as
packers and other devices. Up to seven double acting pistons such
as ICV's, ball valves, and recirculation devices could be handled.
Alternatively, different combinations of single and double devices
could be handled, such as a combination of five double action and
five single action devices. Alternatively, a single code could
close all devices, with the remaining codes dedicated to the
selective operation of different devices as previously
described.
The variable of time can also be incorporated into the well control
system. Activation time for a hydraulic line can be controlled
through absolute time operation, by the duration of pulse
operation, by a combination of different pulses sequenced by
duration or time or relativity within a control order, or by other
techniques.
Although the preferred embodiment of the invention permits
hydraulic switching of the lines for operation of downhole well
tools such as ICVs, switching functions could be performed with
various switch techniques including electrical, electromechanical,
acoustic, mechanical, and other forms of switches. The digital
hydraulic logic described by the invention is applicable to
different combinations of conventional and unconventional switches
and tools and provides the benefit of significantly increasing
system reliability and of permitting a reduction in the number of
hydraulic lines run downhole in the wellbore. As used herein, the
term "downhole" refers not only to vertical, slanted and horizontal
wellbores but also refers to other remote control applications
requiring tool actuator control. For example, the invention is
applicable to subsea control applications in shallow or deep water,
and to the conversion of geothermal energy into usable power.
The invention permits operating forces in the range above ten
thousand pounds force and is capable of driving devices in
different directions. Such high driving forces provide for reliable
operation where environmental conditions causing scale and
corrosion increase frictional forces over time. Such high driving
forces also provide for lower pressure communication ranges
suitable for providing various control operations and
sequences.
The invention controls multiple downhole well tools while
minimizing the number of control lines extending between the tools
and the wellbore surface. A subsurface safety barrier is provided
to reduce the number of undesirable returns through the hydraulic
lines, and high activation forces are provided in dual directions.
The system is expandable to support additional high resolution
devices, can support fail-safe equipment, and can provide single
command control or multiple control commands. The invention is
operable with pressure or no pressure conditions, can operate as a
closed loop or open loop system, and is adaptable to conventional
control panel operations. As an open loop system, hydraulic fluid
can be exhausted from one or more lines or well tools if return of
the hydraulic fluid is not necessary to the wellbore application.
The invention can further be run in parallel with other downhole
wellbore power and control systems. Accordingly, the invention is
particularly useful in wellbores having multiple zones or connected
branch wellbores such as in multilateral wellbores.
Each downhole well tool is assigned a discrete identification
address and reacts only to the assigned address code distributed
through the hydraulic lines. Other address codes not correlating
with the assigned code are ignored by the downhole tool. Actuators
can be positioned downhole to identify the assigned code and for
actuating operation of an engaged well tool or combination of
tools. In this manner, selected well tools can be operated with
full hydraulic power without actuating other well tools, and the
efficiency of each individual hydraulic line is increased by the
combination of multiple lines in the manner indicated.
Although the invention has been described in terms of certain
preferred embodiments, it will become apparent to those of ordinary
skill in the art that modifications and improvements can be made to
the inventive concepts herein without departing from the scope of
the invention. The embodiments shown herein are merely illustrative
of the inventive concepts and should not be interpreted as limiting
the scope of the invention.
* * * * *